The present invention relates to an electro-optical device such as a liquid crystal display device, an organic electro-luminescent (EL) display device or the like, and an electronic apparatus including the same.
An liquid crystal display device which uses a liquid crystal as an electro-optical material is a display device which takes the place of a cathode ray tube (CRT), and is widely used in a display unit of various information processing apparatuses or a liquid crystal TV or the like.
Such a electro-optical device has, for example, an internal driving circuit including a scanning line driving circuit and a data line driving circuit provided on a substrate, an internal driving circuit such as a scanning line test circuit and a data line test circuit or the like, and a plurality of terminals electrically connected to the internal driving circuit. In addition, components are mounted on the plurality of terminals, and predetermined type signals are supplied from an external driving circuit connected to the components. In addition, the internal driving circuit drives and scans a plurality of pixels to have images displayed or to have pixel defects or the like tested, based on the predetermined type signals supplied through the plurality of terminals.
Since the electro-optical panel of the electro-optical device is fabricated in a large-sized manner and its built-in circuits have various functions, it has a tendency that wiring lines for signals supplied from an input terminal of the electro-optical panel become thicker and the number of the wiring lines also increase.
FIG. 1 is a plan view showing a layout of wiring lines in accordance with a conventional electro-optical panel. In the conventional electro-optical panel, a plurality of main signal wiring lines 32, 34, and 36 having large wiring line widths, respectively is arranged parallel to each other per unit circuit. In addition, signals which have been transmitted through the main signal wiring lines 32, 34, and 36 are supplied from the plurality of main signal wiring lines 32, 34, and 36 to thin film transistors (TFTs) 52 constituting the internal circuit through sub signal wiring lines 62, 64, and 66, respectively.
As such, with the structure that the plurality of main signal wiring lines 32, 34, and 36 is arranged parallel to each other and signals are supplied from the main signal wiring lines 32, 34, and 36 to the internal circuit per unit circuit, the sub signal wiring line 62 supplies to the internal circuit the signals which have been transmitted through the main signal wiring line 32 and which is bridged over the main signal wiring lines 34 and 36. For this reason, the number of crossing areas between the sub signal wiring line 62 and the main signal wiring lines 34 and 36 increases, which leads to an increase in the crossing capacitance between the wiring lines. As a result, when the wiring parasitic capacitance increases, a signal transmission is delayed, which results in causing a problem that the signal may not be raised or fallen within an expected time. To cope with the problem, there exists a liquid crystal display device which decreases the time constant by increasing the wiring line width to decrease the wiring resistance or decreases the parasitic capacitance by means of research on the circuit (for example, see Patent Document 1).
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 10-199284.
However, when the wiring line width increases to reduce a resistance in order to reduce the signal delay accompanying the increase of the crossing capacitance between the wiring lines in the conventional liquid crystal display device, the crossing areas accompanying the increase of the wiring line width increases, so that the crossing capacitance between the wiring lines also increases. As a result, since the parasitic capacitance increases, the effect of decreasing the time constant accompanying the increase of the wiring line width is insignificant. On the other hand, when the parasitic capacitance decreases by means of the research on the circuit, the circuit structure becomes complicated.
Accordingly, the present invention is designed to solve the above-mentioned problems, and it is an object of the present invention to provide an electro-optical device and an electronic apparatus which is capable of overcoming the above-mentioned problems. This object is composed of a combination of features described in independent claims in the claims. In addition, dependent claims define specific examples which are advantageous for the present invention.